"This planet is too small. The whole world is like a graveyard."
"Come back with us"
"I haven't traveled far enough yet... got a lot of dirt to shake off my shoes, and right now there's a cold fusion cruiser surfing the ion reefs; just at the edge of the solar system... just waiting to open its transport dock. I just have to send the signal..."
"Are you ever coming back, Jack?"
"What for?"
"For me..."

"There's one thing I always meant to ask Jack. Back in the old days. I wanted to know about that Doctor of his. The man who appears out of nowhere and saves the world. Except sometimes he doesn't. All those times in history when there was no sign of him, I wanted to know why not. But I don't need to ask any more. I know the answer now. Sometimes the Doctor must look at this planet and turn away in shame. I'm recording this in case anyone ever finds it, so you can see... you can see how the world ended."